261401818836 has 12 divisors (see below), whose sum is σ = 609937577312. Its totient is φ = 87133939608.

The previous prime is 261401818819. The next prime is 261401818883. The reversal of 261401818836 is 638818104162.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10891742440 + ... + 10891742463.

Almost surely, 2^261401818836 is an apocalyptic number.

It is an amenable number.

261401818836 is an abundant number, since it is smaller than the sum of its proper divisors (348535758476).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261401818836 is a wasteful number, since it uses less digits than its factorization.

261401818836 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21783484910 (or 21783484908 counting only the distinct ones).

The product of its (nonzero) digits is 442368, while the sum is 48.

The spelling of 261401818836 in words is "two hundred sixty-one billion, four hundred one million, eight hundred eighteen thousand, eight hundred thirty-six".